September 9, 2009
Oral sex may be extremely common among people in the U.S. who consider it a "low-risk" activity. But oral sex may be riskier than many think -- and, no, we're not talking about HIV. We're talking about human papillomavirus (HPV), which has been linked to some types of oral cancer.
Many people engage in oral sex as a form of "safer sex" -- in part as a response to HIV/AIDS prevention campaigns of the 1990s that cast sexual intercourse as dangerous. In that light, oral sex began to look like less of a big deal.
HPV is the most common sexually transmitted disease in the United States. It's easy to transmit: Nearly half of sexually active people will get HPV at some point in their lives, and it's even more common among people with HIV.
The virus can be transmitted through skin-to-skin contact; but the skin needs to be somewhat broken -- it passes best through deep-but-microscopic tears in the thin layer of cells that covers the body's outer surfaces (known as the epithelium).
"There has to be some micro-laceration that allows HPV to get access to those deep cells, the cells at the basement of the epithelium, in order to affect them. That's why you don't just get HPV from shaking hands," explains Francisco Garcia, M.D., M.P.H., an authority on HPV and a professor of obstetrics and gynecology at the University of Arizona.
However, where those cuts exist, HPV can be transmitted, Garcia notes. And those cuts can form nearly anywhere, be it during sex or any number of other activities. "That can be in the vagina," Garcia says. "It can be in the rectum. It can be in the skin of your hand. It can be in your feet. That's what plantar warts are -- what common warts are. Or it can be in what is known as your oropharynx," i.e., the back of your throat.
Once a person is exposed to HPV, two things can happen, Garcia says: "It can either do nothing, or HPV can actually be integrated into the genetic material of the new person. When it does that, that's when there's a potential for infection and damage."
HPV is a sneaky sexually transmitted infection, often occurring without a single symptom. However, HIV-positive people are at higher risk for developing more stubborn symptoms than HIV-negative people -- including genital warts and a condition called dysplasia, which can potentially lead to cancer.
Health care providers and researchers have known for a while about the connection between HPV and certain types of cancer -- including cervical and anal cancers as well as cancers of the throat area. Despite this, most HIV-positive people and HIV-negative people who are sexually active seem largely unconcerned about the risks of HPV -- and even less so about the risks of oral HPV.
But this may be about to change. Oropharyngeal cancers (cancers of the back of tongue, the pharynx and the tonsils) are on the rise, according to recent studies, particularly a landmark study published in the September 2009 issue of the journal Cancer Prevention Research. HPV is to blame in a significant number of those cancers -- and one strain, HPV-16, which is also responsible for most cervical cancers, seems to be the culprit.
The overall number of these HPV-related oropharyngeal cancers is low, but we may be on the edge of an epidemic in cancers of the throat area, according to Scott Lippman, M.D., of the M.D. Anderson Cancer Center in Houston, Texas. "This is likely to become one of the most common tumors that we see in the next five or 10 years, if the patterns persist," said Dr. Lippman at a recent press conference.
The patterns Lippman is referring to have to do with the sexual activities of people in the U.S., which have changed dramatically over the last 50 years. During the sexual revolution of the 1960s, oral sex saw a boom in popularity. Since it can take several decades from an HPV exposure to become HPV-positive cancerous tumor, it seems that for a growing number of people, the sexual revolution of yesteryear has become the tonsil cancer of today.
There's some good news, though: The Cancer Prevention Research study found that cancers of the throat area that come from HPV are actually easier to treat than similar cancers that develop from other risk factors, such as smoking or drinking alcohol.
Until about 20 years ago, the average person with cancer of the throat area was a heavy user of alcohol or tobacco, Dr. Lippman says. Today, people who develop throat cancer may have no other risk factor besides HPV.
Further, HPV-positive tumors are very different from their cousins that grow from excessive smoking or drinking, according to Kevin Cullen, M.D., the senior author on the Cancer Prevention Research study. Researchers are still trying to make sense of all the differences, but one important thing they've discovered is that HPV-positive tumors have fewer of the genes that resist chemotherapy than do HPV-negative tumors. This means that, for the most part, people with HPV-positive tumors can breathe a sigh of relief since there's a good chance they'll do well on treatment.
It's also important to note, again, that HPV-positive oral cancer is not all that common. Considering how common oral sex is, how prevalent HPV is (an estimated 20 million people in the U.S. are walking around with HPV at any given time) and how relatively uncommon cancers of the tongue and tonsil are (they account for less than three percent of all cancers in the U.S., according to the National Cancer Institute), it's clear that just because someone has HPV does not mean that cancer is definitely in their future.
Researchers still understand very little about HPV infection in the throat area. However, the HPV vaccine, which is currently recommended in the U.S. for all girls and women between the ages of 9 and 26, should eventually be able to eliminate HPV-related throat and tonsil cancer once and for all, Dr. Cullen says. The vaccine prevents a person from becoming infected with the types of HPV that are most commonly associated with cancer, including HPV-16. Because the vaccine is not known to be effective in people who have already been exposed to HPV, there's a push to get children vaccinated before they've had any sex at all.
Many studies of the HPV vaccine in men and boys have shown good results -- and an outside expert panel to the U.S. Food and Drug Administration recently recommended its approval for that use.
Meanwhile, it's clear that the U.S. needs to do a better job at stepping up oral sex education and risk-reduction efforts, not only with youth and teens, but with adults as well. We all need to be aware that oral sex is not just good, clean fun after all, and take appropriate steps to keep ourselves safe, whether that means using dental dams and Saran Wrap, or making sure to get checked often for HPV (i.e., make sure your doctor checks your mouth and throat) for early signs of potential HPV-related cancer.
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